So this is a work around that seems to work 100% of the time. Trust me when I say I have tried EVERYTHING else! 1. Both players load the game and go to the tower. 2. Both player at the same time press the XBOX button and quit the game. 3. Both players at the same time start destiny again and this should generate a 'WEASEL' error. This should usually happen to both players. 4. Close the error and continue to selecting your characters. 5. You should now be able to join the same fireteam team. I know it's a ball ache it this does genuinely work. You can even leave the fireteam after and you will have no issues rejoining. This is a fix for as long as you are online but the next time you play you will have to do this again. Just goes to show that this is truly a bungie issue as to get this to work no changes to any network settings need to happen. Hope this helps

Figured i would respond - i hope you all can see this.... So i must say huge shout out to Durandal for taking the time to talk dumb to me. I greatly appreciate it. I think i have found the solution - it was settings that i couldnt see on my side for my gateway. I spent about 45 mins on the phone with my ISP - and whatever the bloke did seems to have worked. Now i know it may not have anything to do with Destiny itself, but her increased some bandwidth - and did some other things - i havent looked yet. I was so excited to be able to play with my wife i didnt care. Ill check out my gate way settings tonight and respond to this so maybe someone with the same issue can replicate it to resolve it. That aside -- i have a question. Does it matter if 1 xbox is on a 2.4 band and the other is on a 5.0 band? Thanks and ill see you out there.

I had the same problem, except I was having this issue on PS4. I tried every solution possible; port forwarding, DMZ, bridged, etc. I also have 2 routers with one PS4 wired and the other wireless (using Comcast as well). In the end I opened ports and reserved an IP address on the router with the wired PS4. I opened ports per Bungie's recommendations which can be found here: https://www.bungie.net/en/Help/Article/11931 You can find all the info you need for configuring your router through this site: https://portforward.com/help/destiny/ Anyway, did all that and still could not connect with my son's PS4. This was extremely frustrating as we could connect on other online games and chat with zero issues. So, as a last ditch effort we tried something I have not seen or heard of by anyone else with this issue. We created a private chat party, then we linked up online and played a match of CoD infinite warfare (this works with any game which both consoles are able to connect on). After completing one quick game of team death match together (any game mode works) we stayed in our chat party and both migrated to Destiny. Once in orbit I simply opened up the roster and chose Join fire team under my son's gamer tag and voila I was able to join my son's fire team with no issues. We've been doing this since Christmas and it works every time. Kind,of a pain in the butt, but it's a good work around. Don't know if this will work for Xbox One, but it's worth a try. Hope this helps if you haven't already resolved this issue.

This is an issue that Bungie is actively investigating. Keep an eye on this thread for more updates/information https://www.bungie.net/en/Forum/Post/219463451/0/0